Once a user grants permission, the Geolocation API provides access to geographical location information from device.

• Editor's draft

This HTTPs-only API exposes the navigator.geolocation object with a couple of useful methods:

• .getCurrentPosition(successCallback, [errorCallback, options]) - "one shot" position request
• .watchPosition(successCallback, [errorCallback, options]) - Watch a position and get notified of any changes.
• .clearWatch(someId) - allows you to stop watching for location changes.

No location information is made available through this API without the user's permission.

Request the user's current location. If the user allows it, you will get back a position object.

navigator.geolocation.getCurrentPosition(position => {
  const { latitude, longitude } = position.coords;
  // Do something cool with latitude, longitude
});

Request the ability to watch user's current location. If the user allows it, you will get back continuous updates of the user's position.

const watchId = navigator.geolocation.watchPosition(position => {
  const { latitude, longitude } = position.coords;
  // Do something cool with latitude, longitude
});

Finally, stop watching the user's location.

navigator.geolocation.clearWatch(watchId);

The specification provides examples covering different use case.